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Tang B.,China Institute of Technology | Zhao Y.,China Institute of Technology | Li L.,China Institute of Technology | Wang L.,China Institute of Technology | And 5 more authors.
Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering | Year: 2014

The dynamic characteristics of suction valves for reciprocating compressor with a stepless capacity control system are studied in this article. The self-acting valve model that is applicable for stepless capacity control condition is derived. For the suction valve movement controlled by actuator, a simulation of the hydraulic and mechanical system is conducted. An experimental platform is setup, which is used to test the valve dynamic when it is controlled by actuator. The results from the mathematical model show that the valve impact speeds are influenced by the valve lift, Mach number of the flow in the valve clearance and the initial crank rotation angle of the valve closing process. The simulation results agree well with experimental results. The simulated maximum speed is about 0.53 m/s, and the maximum speed tested by experiment is about 0.58 m/s, both of which are much lower than the speed of the automatic valve (3 m/s). In addition, simulation results show that the maximum speed is at constant when the hydraulic piston stroke increases, which is much different from the automatic valve. It becomes apparent from the aforementioned results that with stepless capacity control system the dynamic characteristics of the suction valve are changed. The valve can be limited at a low speed, and the valve impact speeds to seat and stopper decrease significantly, which would be helpful for extending the life of the valve plate. © IMechE 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Tang B.,China Institute of Technology | Liu G.,China Institute of Technology | Xu H.,Shanghai HuanTian Industrial Co. | Yang Q.,China Institute of Technology | And 3 more authors.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2014

Vibration faults of a large process reciprocating compressor system were analyzed. The unbalanced forces/moments were firstly calculated, and the vibration amplitude of compressor foundation was checked. Finite element models of shafting of compressor-motor and fluid structure interaction of pipeline systems were constructed, respectively. The first six orders vibration mode and frequency of shafting were obtained by the FEM, and the natural frequency of pipeline system was also calculated by FEM. The results show that the vibration amplitude generated by unbalanced moments is acceptable. The main causes of compressor system vibration faults are from fluid structure interaction vibration of pipeline system. Operating speed of compressor has to be changed to avoid the resonance region of shafting vibration. An improvement program of pipeline system was proposed, by which the natural frequency was increased obviously, and the vibration amplitude decreases to 165 μm that meets the demands of standard API618 well.

Bin T.,China Institute of Technology | Yuanyang Z.,China Institute of Technology | Liansheng L.,China Institute of Technology | Guangbin L.,China Institute of Technology | And 5 more authors.
Applied Thermal Engineering | Year: 2013

On the basic principle of stepless capacity control system for large reciprocating compressor, the thermal cycle was analyzed. The equations for the process of suction, reverse flow, compression, discharge and expansion of clearance gas were established. According to these equations, p-V diagrams at various situations were simulated. An experimental platform was setup and the compressor with designed stepless capacity control system run well. The experimental results show that the capacity of compressor can be regulated steplessly, and the motor power is reduced proportionally with respect to the reduction of capacity. During the suction process, both the flow resistance of valve and the pressure fluctuation in cylinder can be reduced by opening the suction valves with the actuators. The simulated and experimental results showed good coincidence. The clearance volume and valve clearance Mach number had a negative influence on the thermal performance of compressor with stepless capacity control system. © 2013 Elsevier Ltd. All rights reserved.

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